*** Notice: This was submitted to the guide team a while ago, but never added on-site (This game probably is not a high priority for them). If someone can write a better one which will meet approval before mine, help yourself. In the mean time, I thought I would post this so anyone looking at this game has a good idea how to do it. I 1'ked Orochi 2 and endorse this plan***

The achievements for Orochi 2 aren't really hard in terms of skills, but they can be unbearably time consuming. This road map is written with the explicit purpose of keeping you alive from the moment you pop the game in for the first time all the way to 1000 points. "All Stages Cleared" requires each level to be completed on each of the 4 difficulty levels (that makes for a total of over 200 levels). For more information on specific achievements, refer to the achievement guide posted by Tricka21.

Part 1: The First Playthrough

Start by playing survival mode and winning a match. Once you're done, save your game for an extremely easy 40 points. Savor that, as everything else requires work.

Play through each faction's story mode on easy, to unlock the levels, and begin leveling up characters. Since some of the Dream Mode levels require quite a bit of grinding, do not use an officer after you've leveled them to 99 with 50 proficiency, as you won't be getting any closer to unlocking stages. I recommend starting with the Wu story, so you'll have the best grinding level (Wu 4) available ASAP. I'd recommend grinding characters for as long as you can stand as soon as that level is available, so you'll have some stronger officers for the other stories, and so you'll have fresh content to look forward to after grinding sessions for as long as possible (see Part 2: The Grind for more info). Follow the treasure guide from RaZeDieFox, and try to get as many as you can on the first try. You can replay levels with more powerful characters to get the ones you missed. Also concentrate on getting every ability from every officer you use.

Part 2: The Grind

The last Dream Mode level you'll unlock requires a total proficiency level of 2,730 across all officers. This is akin to maxing out the proficiency of 54.6 characters... Now you can see why the game takes so long. Before grinding a character in earnest, it's best to get them their level 4 weapon. I recommend taking a level 99 Orochi with the best weapon you have for him and running Samurai level 1 on Chaos difficulty, with two other characters who need weapons. The level takes under 5 minutes to complete, and killing the officers will net 4 weapons for your characters.

With satisfactory weapons in tow, keep running Wu 4 over and over killing officers until a character is level 99 with 50 proficiency, then move on to another. Excess growth points can be used to level other characters up. I recommend finding some custom music you like, as this phase takes an eternity. Focus on characters that must be leveled up to unlock levels, and characters that have Dream Mode levels, before moving on to other characters.

I averaged about 60 proficiency levels an hour, meaning the grind would take about 45.5 hours to complete. This time will be reduced by leveling up some characters as you play through the stories. My point is be ready for a very long and boring slog.

Phase 3: Difficulty Clearing and Weapon Grinding

When you're ready to clear the story levels on each difficulty, I recommend using the same 3 characters over and over, and using them as your weapon factories. You want to take every weapon they get and focus on cranking out as many copies of Almighty as you can, as it makes Chaos levels much easier. I recommend at least 1 of the 3 characters for each Dream Mode level has Almighty on their level 4 weapon. Revival and Supremacy also help, but aren't required.

In Free Mode, the story levels are a breeze, even on Chaos, with a level 99 Orochi with the following weapon:

You can finish the Dream Mode levels for the first time any time you want, to begin earning the achievements for completing levels. However, clearing them all on every difficulty will be the last thing you do on the road to 1000. If you've been following along, most of the characters who have Dream levels should already be level 99 with 50 proficiency and level 4 weapons. Take the time to upgrade character's weapons to their fullest, so they look like the Orochi weapon posted above, and at least 1 of the 3 characters in every level has Almighty. Simply beat each level on every difficulty and you'll have finally earned every achievement!

Conclusion:

With proper planning, the points in Orochi 2 aren't very hard, but the extremely long grind to unlock the final Dream Mode level may test the limits of your sanity.

Only thing I have to add though is that for the weapon harvesting on Samurai level 1 on Chaos difficulty, you can kill Goemon but he only drops a 3rd weapon box (I tried killing just him then going after Dong Zhuo and that's the only weapon I had) whilst going straight for Dong Min then ending the level straight after got me the 4th weapon (for Pang Tong who was on level 1 and not played as and a leveled up Sun Quan wth a level 99/50 proficiency Orochi as my 1st character)

Don't know if that's been of help to anyone but it's what I found on my playthrough earlier.

Somehow i cant agree with the difficulty to be 4, maybe 6 or 7 due to the fact you have to beat every scenario at EVERY difficulty

i disagree. put Almighty on any fourth weapon with the following stats and Chaos mode is a breeze with anyone: flame, ice, bolt, slay, flash, brave, might, and range.

each dream stage has at least one character that has a decent moveset to use in conjunction with an Almighty weapon. as for free mode stages, just use characters you're comfortable with and equip them with a weapon that has almighty

Instead of a lvl99 Orochi. I use a lvl99 SunWuKong if you use his xxxxy combo with Slay10, Bolt10, Reach10, Might10 and Flash10 (other 2 is your choice)

It is pretty much a insta-kill when comes to 90% of the officer. Some officers like Leaders, LuBu, Tadakatsu Honda and Keji, take 2 good hits. Plus SunWuKong is as fast as Red Hare so completeting the levels go much faster.